Manufactured buildings, such as manufactured or mobile homes and offices, are constructed and assembled at an initial manufacturing facility, and then moved on wheels to the installation site. The manufactured building typically includes long, longitudinal support beams underneath the building to support the floor of the building. During typical installation, a plurality of piers are placed between a ground surface and the support beam to support the building on the site. The piers sit on or are attached to footings such as metal plates or pans, plastic plates, or concrete pads placed on the ground.
Different types of piers are known. One type of pier uses stacks of blocks that sit on footings and transfer load from the support beam. Other piers use metal tubular members that connect between a ground pan and the support beam.
Some foundation systems for manufactured buildings also resist lateral and longitudinal wind and/or seismic forces on the building. These foundation systems typically use a ground pan and an elongated strut connected at a lower end to the ground pan and at the upper end to a support beam of the manufactured building. The elongated strut can be oriented parallel to a longitudinal axis of the support beam or extend laterally from underneath one support beam to connect to the adjacent support beam of the manufactured buildings, or both. Such foundations provide resistance to wind and/or seismic forces in the lateral and longitudinal directions.
Often the support beam is positioned inwardly of a perimeter of the manufactured building. The floor structure of the manufactured building includes a plurality of joists that are positioned in spaced-apart relation and transverse to a longitudinal axis of the support beams. The joists extend outwardly of the support beams to a perimeter wall of the manufactured building.
While the piers and foundation systems have been successful in supporting installed manufacturing buildings and resisting wind and/or seismic loads on installed manufactured buildings, there are drawbacks to these systems. Laterally extended portions of floor of the manufactured building may sag over time, for example, due to settlement of the ground under the piers of the manufactured building. The manufactured building may become out of level. Further, frost heave can reduce holding and supporting capability of foundation members. Heave in soil occurs when the water in the ground freezes. The freezing water expands, and causes the ground to heave up or rise up or swell. Frost heave causes the foundation ground pans (or pads) to move. This movement is communicated to the house through the elongated struts between the ground pan and the support beam, and may contribute to the house becoming out of level. A manufactured building that is not level can result in openings in the manufactured building becoming out of skew. This causes doors, such as in exterior doorways, to become skewed and not open or close properly. Windows in perimeter walls likewise become difficult to open and close.
It is believed that there are three factors that contribute to frost heave. These factors are the soil being sufficiently saturated with water, the atmospheric temperature, and the duration of the saturation and cold temperatures. Efforts to resist frost heave have been made. Typically in areas that experience significant frost heave, the foundation must be engineered and extend below the frost line. This requires excavation of an in-ground footing and installation of a rigid or engineered foundation such as concrete footers and pilings. In other areas, skirting attaches around the perimeter of the manufactured home. The skirting extends from a lower edge of the manufactured home to the ground. The skirting encloses the space between the ground and the bottom of the manufactured home. Skirting used on the perimeter of manufactured buildings placed at sites with pier supports is not entirely successful in reducing or eliminating frost heave. Even with skirting, manufactured buildings placed at sites with periphery pier supports and not having engineered foundations, are susceptible to frost heave of the ground below the ground pan or pad.
To provide foundations that resist the effects of frost heave, installers dig holes below the frost line and fill with concrete. Connecting members, embedded in concrete, connect to the manufactured building. However, digging foundation holes and pouring concrete foundations is time-consuming, costly and difficult, particularly during periods of freezing weather.
Accordingly, there is a need for a ground anchor to support manufactured buildings. It is to such that the present invention is directed.